Evaluation the effect of thickness on tear strength of some types of alginate impression and compare their dimensional accuracy with addition silicone after repeated pouring

Abstract

Alginate impression material is widely used in dentistry due to its low cost and ease of use. However, the disadvantage of hydrocolloid impression materials is their dimensional change and low tear strength. The aim of this study was to evaluate the dimensional stability of the dental cast obtained from the alginate, addition silicone impression of the acrylic model after repeated pouring, and the dimensional stability of the alginate impression after different storage times(1/8 day, 3days, 5days and 9days). The tear strength of alginate impression materials of different thicknesses was also evaluated (2mm, 3mm and 4mm).Regarding the dimensional stability, the analysis showed that repeated pouring of impression materials had no statistically significant effect on dimensional stability where p > 0.05, with the exception of the conventional type. Also, the analysis showed there was no significant difference in dimensional accuracy of the casts poured after 5 days of alginmex impression, Also there was no significant difference in dimensional accuracy of the casts poured after 9 days of cavex impression materials, where the p-value > 0.05. While there was a significant difference in dimensional accuracy of the casts poured after 9 days of alginmex impression. In tear strength analysis, there was no significant difference in tear strength between three different thicknesses of alginate impression materials, Where the p-value was (0.611,0.969, 0.516) for alginmax, cavex, and conventional materials respectively. Conclusion: clinically acceptable casts can be obtained by the double pour of new-generation alginate materials. The dimensional stability of alginate impressions was directly influenced by the type of alginate and the time of poured the impressions after the different storage times. Alginmax could be poured after 5 days and Cavex impression could be poured after 9 days of storage with no significant dimensional changes. There is no difference in tear strength between the three different thicknesses of each type of alginate impression material.